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Isolepis cernua

fiber-optic grass

Cyperaceae

Europe, North Africa, western Asia, and Australasia

Deer Resistant Container Friendly

SunFull Sun – Part Shade

WaterHigh

HardinessZones 8–10

Overview

Isolepis cernua is a tufted, grass-like perennial sedge growing 4-8 inches (10-20 cm) tall, forming dense, rounded clumps of slender, thread-like stems that arch outward and trail at the tips. Each bright green stem ends in a tiny, pale, rounded flower head 0.1 inch (2-3 mm) across, which sits like a bead at the stem tip and gives the plant its fiber-optic name. The slender stems move with the slightest air movement and lean over the edges of pots and pond margins. The clump stays evergreen in mild conditions and grows actively through the warmer months. Plants reach full size within a single season. Isolepis cernua grows in full sun to part shade on permanently moist to wet soil, including the shallow margins of ponds and the surface of constantly watered containers. It needs steady moisture and browns quickly if the roots dry out. The plant is short-lived, often declining after two or three years, and is damaged by hard frost below about 25F (-4C). It is frequently grown as a container or houseplant where its moisture needs can be met.

Native Range

Isolepis cernua is native to coastal and wetland habitats across much of Europe, North Africa, western Asia, and Australasia, where it grows in damp sand, marshes, and the margins of fresh and brackish water.

Suggested Uses

Grown in containers, bog gardens, and at shallow pond margins where the soil stays wet, spaced 6-8 inches (15-20 cm) apart. Used as a houseplant in a watertight container stood in water. Planted at the edges of pots and ponds where the arching stems trail over the rim.

How to Identify

Identified by dense tufts of slender, thread-like bright green stems 4-8 inches (10-20 cm) tall, each ending in a tiny pale, rounded flower head about 0.1 inch (2-3 mm) across at the tip. The arching, trailing habit and beaded stem tips give a fiber-optic look. The clumping, rush-like growth separates it from true grasses.

Appearance

Size & Dimensions

Height4" - 8"

Width/Spread6" - 1'

Reaches mature size in approximately 1 years

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~12 weeks

Summer

Small pale flower heads sit at the tips of the stems through summer and are present for much of the growing season. They are tiny and grade from greenish to straw-colored. Seeds follow but the heads remain on the stems.

Detailed Descriptions

Foliage Description

bright green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.0(Neutral)

357912

Soil Types

loam peat sand

Drainagewet

Water & Climate

Water Needs

High

Frost Tolerance

tender

Time to Maturity

1 year

Care & Maintenance

Care Guide

Grow in full sun to part shade on permanently moist to wet soil, or stand containers in a saucer of water to keep the roots wet. Water freely and never let the soil dry out, as the stems brown rapidly in drought. Trim off browned stems through the season to keep the clump fresh. Divide clumps in spring to propagate and to renew older, declining plants. Hard frost below about 25F (-4C) damages the foliage, so in cold regions it is grown under cover or as a houseplant. The plant is short-lived and is replaced or divided every few years.

Pruning

Trim away browned or tired stems at any time to keep the tuft looking fresh. Cut the whole clump back if it becomes scruffy, and new stems follow from the base. Divide rather than hard-prune to renew old plants.

Pruning Schedule

summer